A communication network for a geographic area, such as a metropolitan area, may have a ring topology. As an example, a synchronous optical network (SONET) system may comprise a ring with nodes. In operation, channels of packets travel through the nodes. A node may add or drop channels in order to direct the packets through the ring.
A node may include a wavelength device with a reflective device that is used to add or drop channels. According to known techniques, the reflective device has a fixed passband for each channel. A fixed passband for each channel, however, may be inefficient in certain situations. It is generally desirable to be efficient in certain situations.